How can I react on an UIApplicationDidReceiveMemoryWarningNotification ?

Question

When memory becomes low, the System would send that UIApplicationDidReceiveMemoryWarningNotification notification. But I don't get it... that isn't a Method I must implement in my App Delegate, right? How do I get this notification?

Answer 1

You would implement the "applicationDidReceiveMemoryWarning:(UI Application *)application" in your app delegate.

This is a warning notification telling you that you are about to exceed your memory limitation, at which point, the OS will kill your application process - in the applicationDidReceiveMemoryWarning you have the chance to free up and release some memory to prevent the OS from killing your app.

@interface MyApp: NSObject <UIApplicationDelegate>
{
}
@end
@implementation
-(void)applicationDidReceiveMemoryWarning:(UIApplication *)application {
  [[TextureMgr sharedTextureMgr] removeAllTextures];
}
@end

That's the standard 'Cocos2D-iphone' implementation of the function.

Answer 2

Your app delegate can implement the -applicationDidReceiveMemoryWarning: method. Other objects can register as observers for UIApplicationDidReceiveMemoryWarningNotification. See the section in the docs on "Managing your memory usage", at http://developer.apple.com/iphone/library/documentation/Performance/Conceptual/ManagingMemory/Articles/MemoryAlloc.html#//apple_ref/doc/uid/20001881-SW1